This invention relates to tofu food products, and to the methods of manufacturing them. More particularly, it relates to simulated meat products or meat analogs, and to the methods by which they are made.
For convenience in describing this invention, traditional tofu manufacture from soybeans has been used. Tofu is made by a process in which whole soybeans are soaked, ground, mixed with water, heated to produce a slurry, and filtered so that the ground soybean residue is separated from the liquid. The resulting curd is coagulated from the whey portion of the soymilk by the use of acids and/or salts. "Tofu" is the most widely used English language term for this product but it has also been called "soybean curd", "bean curd", and "bean cake". It is typically classified into three general groups: traditional, non-traditional, and specialty. The traditional group is further divided into "pressed" and "silken" tofus and the non-traditional group includes four categories one of which is tofu with fiber. The "tofu with fiber" designation means that the tofu contains all or at least 75% of the dietary fiber in the soybean cotyledons and/or seed coat that is normally removed in the process of making soymilk from whole soybeans. As will be apparent, this is very different from the fiber/tofu food product of the present invention.
Much work has been done to provide satisfactory meat analog food products from inexpensive texturized vegetable protein particles, including soybean. Examples of such products include those described in the following U.S. Pat. Nos. 3,772,035, 3,914,443, 4,061,784, 4,132,809, 4,265,917, and 4,275,084, each of whose contents are hereby incorporated by reference. To be accepted as a simulated meat substitute, a product must have a certain texture which imparts the appearance, chewy texture, and mouthfeel associated with meat. The chewy texture refers to and includes the physical characteristics of protein material which gives it a feeling of resilience, elasticity and resistance to shear when chewed. Although this chewy texture is preferably evaluated subjectively by chewing the protein, it alternatively can be measured objectively by measuring its shear and press value, such as, for example in the method described in U.S. Pat. No. 3,778,522.
To be suitable, the meat analogs must also bind effectiveIy. In the past this was accomplished by using binding materials which were either entirely or partly made of egg white. However, the relatively high cost of egg whites increases the price of what otherwise are cheaper meat analogs. Some examples of such binding materials and meat analog products are described in U.S. Pat. Nos. 4,061,784, 3,343,963, and 3,594,192 and 3,914,443, the contents of each of which is incorporated by reference. Ovalbumin (or egg albumin) when used as the sole binder for certain preparations requires heating and rehydration, and often results in a product that lacks juiciness and a desirable meat-like mouthfeel. Other compounds have been used as binders but they have limited physical/chemical properties.